1. Field of the Invention
The present invention is directed to a switch that is used to test a vacuum created by suctioning air through a hole. The invention has particular utility in the printing field, where the switch may be used to test a vacuum that is created between a media support surface, such as a print drum, and a print medium by suctioning air through a port hole in the media support surface.
2. Description of the Related Art
Printing systems of the type described herein operate by holding a print medium, such as a metal plate, against a media support surface, such as a print drum, and etching images onto the print medium using a laser. The accuracy of this type of printing system is dependent, at least in part, upon how securely the print medium is held against the media support surface. More specifically, when the print medium is not held securely against the media support surface, print errors may be caused due to wrinkling of the print medium and/or air bubbles underneath the print medium, among other things.
Several ways have been developed to hold a print medium against a media support surface during printing. For example, one way which has proven effective utilizes a vacuum that is generated by suctioning air through port holes in the media support surface. More specifically, in these systems, the print medium is placed against the media support surface and air is suctioned through the port holes in the media support surface, thereby creating a vacuum between the media support surface and the print medium. This vacuum acts to hold the print medium in place during printing.
As might be expected, the efficacy of such systems depends upon the vacuum used to hold the print medium in place. That is, in the event that the vacuum is not sufficiently strong, or has been compromised due, e.g., to blockages, or the like, in the port holes of the media support surface, attachment of the print medium to the media support surface may be adversely affected. As a result, the print medium may wrinkle, or there may be air bubbles or the like trapped between the media support surface and the print medium, thereby increasing the likelihood of print errors.
Thus, there exists a need for a way in which to test a vacuum which will be created between a media support surface and a print medium before printing actually takes place.